Power consumption is an issue relative to electrochemical sensors. Conventional potentiostats have to supply current to the sensor even if the sensor would be capable of generating its own current when operated in a simple two electrode load resistor circuit.
Conventional potentiostats actively force current through the counter/working electrode circuit so as to maintain a desired potential difference between working and reference electrodes. Consumable anode oxygen sensors based on metals such as zinc or tin suffer from issues due to the sensing electrodes being driven to a potential where they can evolve hydrogen. The effect becomes worse at elevated temperatures. Hydrogen evolution on the sensing electrode also results in a background current, additional consumption of the anode, and issues relating to venting the evolved hydrogen from the sensor.